ELASTOPLASTIC ANALYSIS OF SPACE-TRUSSES CONSIDERING THE EFFECTS OF LARGE DISPLACEMENTS AND SOFTENING

A computation-oriented approach for elastoplastic analysis of space tr usses under assumptions of both material and geometric nonlinearities is presented. In particular, a stepwise incremental holonomic (path-in dependent) formulation is developed in a form ideally suited for numer ical solution by a predictor-corrector type algorithm. The proposed ap proach rests on a systematic treatment of sources of nonlinearities th rough the concepts of fictitious forces and deformations. One outcome of this is the preservation of static-kinematic duality, even in the p resence of arbitrarily large displacements. Symmetry of the governing system, cast as a so-called ''mixed complementarity problem'' (MCP), i s however destroyed by the nonsymmetric softening laws adopted. Two nu merical examples are given to illustrate the complexity of the respons e that can arise for even simple structures, as well as the ability of the method to analyze large-size structures.